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Thread: 1917 Gibson A2 mandolin original tuning mechines gear slop

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    Question 1917 Gibson A2 mandolin original tuning mechines gear slop

    Mando fans - They are the original plank-style tuners, four to a plank.. How do I best restore good tuning key shaft with gear fit?. Can a good machinist restore the fit? I do not want to fit this instrument with replacement tuning machines. Any suggestions out there from the forum readers? I am a retired pro guitar player, but have played this instrument for 46 years and a lot more recently. Thank you.

  2. #2
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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    Welcome to the forum.

    See here - http://www.lutherie.net/tuner.maintenance.html or fit a set of StewMac Golden Age “Restoration” tuners. The “relic” versions don’t look that bad. They are possibly the only practical solution for sloppy tuners.

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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    First, even a very good machinist won’t necessarily be able to scope out this without considerable additional information, some of which relates to the mandolin itself. If the problem is on most of the strings, or all, you need to measure where the slop is: actual wear of the spur gear or worm teeth, wear in the plate, wear in the lugs, wear in the peghead wood. A luthier with vintage experience might be able to define a fix that could help a machinist, whether that’s replacing parts or altering what’s there, but by then you’re down to a very small crowd. What I’m saying is that there are more causes than gear wear, and there’s no original blueprint to help.
    Personally, I’d put up with the wear, always tune up to the note, and make sure there’s no string binding at the nut, which also causes apparent play.

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    Moderator MikeEdgerton's Avatar
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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    The Stewmac restoration tuners that will fit your mandolin mentioned by Ray(T) can be found here. I'd replace them and keep the originals in the event that you ever sell it. You can include them in the sale and you have an instrument you can tune.

    What you have should look like this:
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    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    Quote Originally Posted by Gene Sikora View Post
    How do I best restore good tuning key shaft with gear fit? Can a good machinist restore the fit?
    Pictures, please. And yes, likely your tuners can be improved. As you disassemble, clean and inspect them, consider:

    a) they were not built to modern space-age manufacturing tolerances, dimensions and fit can be just wrong. i.e. I often see jaws that hold the shaft set too close together, they bind and prevent the shaft from turning. this is easy to fix by bending them, but you must have correct tools and metal working experience to avoid ruining them forever.

    b) they were built before concept of interchangeable parts was invented (roughly, during/after WW2). likely individual gears and shafts were mixed-and-matched for correct fit. somewhere down the line somebody may have taken them apart, switched them around and they no longer fit together. you may be able to mix-and-match them back together for a better fit.

    c) they have manufacturing defects. I see many brass gears with burrs and incompletely cut grooves. this is easy to fix if you have the right set of files and experience working them. if you do it wrong, you ruin it forever.

    d) installed wrong. plate sits on a bumpy surface at an angle. shaft holes do not align or drilled at an angle. screw holes do not align, etc. this requires woodworking and goes to a competent luthier.

    e) there is plain-bad tuning machines. steel-on-steel gears. badly cut gear teeth. cannot-take-apart designs. corroded, all rusted. just replace them.

    all this said, the $$$ pricey replacement tuning machines look more and more attractive. (installation may require woodworking, so so goes to a competent luthier) (there is reports of brand-new tuning machines not working correctly, see (a-e) above, many places in the world still build to 19th-century tolerances. ovation mandolin south-korean built tuning machines, I am looking at you).

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    Moderator MikeEdgerton's Avatar
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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    Quote Originally Posted by mandocello8 View Post
    ...they were built before concept of interchangeable parts was invented (roughly, during/after WW2)...
    I think you'll find the concept of interchangeable manufactured parts with tight tolerances happened way before WWII.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    Quote Originally Posted by MikeEdgerton View Post
    I think you'll find the concept of interchangeable manufactured parts with tight tolerances happened way before WWII.
    true, so true. especially in fields where it really matters, airplane engines, steam and gas turbines.

    but where I sit, some people still did not get the memo. recently we order a bag of brass screws (non-magnetic application), arrives a bag of what-looks-like-pure-copper screws (red colour, very soft material), same part number, etc. vendor is very sure it's the right stuff. luckily different vendor had brass screws made from non-magnetic brass (we check!). a screw. can you go more common-denominator on "interchangeable component"?!? buying "interchangeable" electronics parts is even more fun. true, mechanically they usually match the PCB soldering location with good precision.

    as applies to mandolin tuning machines, even today, difference between precision manufactured ones and "cheap ones" is like night and day (day and night, autobahn and swamp, that is). the good ones are really good.

    would be interesting to see pictures of OP's tuning machines, curious what went wrong with them. My 1917 A4 still has the original inlayed Handels and they work flawlessly, I never had a reason to take them apart so far.

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    Registered User Steve 2E's Avatar
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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    Quote Originally Posted by Gene Sikora View Post
    I am a retired pro guitar player
    I don't have much to add other than the clean and lube trick has helped out a few of my old mandolins. I'm just curious though, are you the same Gene Sikora that recorded "A Song for Mary" and others?

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    Default Re: 1917 Gibson A2 mandolin original tuning mechines gear slop

    I have '23 A Junior that I restored (got it in 4 pieces) The machines were more than pretty sloppy....Like you I didn't want to taint it with replacement ones. However, I also wanted to play it. I put Restoration tuners (the ones Mike recommended) on it and have the originals with the original bridge in a ziploc bag incase I ever decide to part with it. I get not wanting to change them, but I love playing it.....and it loves staying in tune

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